Google Identity Toolkit (GITkit) helps relying party (RP) websites to support federated login easily (http://code.google.com/apis/identitytoolkit).

Let your users share via their accounts on popular social networks such as Facebook, Google, Twitter, LinkedIn, Vkontakte and over 50 more!

Social Media Share Icons to increase social traffic and popularity. Social sharing to Facebook , Twitter, Pinterest,LinkedIn and Google Plus social media network

Social Login by Janrain